diff --git a/src/hulk/writef.d b/src/hulk/writef.d
index 5f183c3..deebe28 100644
--- a/src/hulk/writef.d
+++ b/src/hulk/writef.d
@@ -88,9 +88,9 @@ size_t writef(string s, va_list args, ch_out_fn ch_out)
  */
 private size_t write_hex(ulong v, bool upper, char pad, size_t width, ch_out_fn ch_out)
 {
-    string hex_chars_lower = "0123456789abcdef";
-    string hex_chars_upper = "0123456789ABCDEF";
-    char[16] buf;
+    static __gshared string hex_chars_lower = "0123456789abcdef";
+    static __gshared string hex_chars_upper = "0123456789ABCDEF";
+    static __gshared char[16] buf;
     size_t i;
     do
     {
@@ -126,7 +126,7 @@ private size_t write_hex(ulong v, bool upper, char pad, size_t width, ch_out_fn
  */
 private size_t write_udec(ulong v, char pad, size_t width, ch_out_fn ch_out)
 {
-    char[20] buf;
+    static __gshared char[20] buf;
     size_t i;
     do
     {